During the manufacturing process of a semiconductor integrated circuit, a sample such as a semiconductor wafer made of silicon or the like as a raw material is held several times on sample stages of a manufacturing apparatus, an inspection device and the like. As a method for holding a sample on a sample stage, various devices and various holding methods have been proposed in accordance with the types of manufacturing processes. As processes of holding a sample, for example, there are a process of grinding the sample into a flawless mirror plane, a process of partially exposing a photo-sensitive material called a resist which applied on a sample by light or an electron beam with a uniform wavelength, a process of eliminating the exposed resist, a process of inspecting the sample which has passed through the respective processes and the like. Further, the surrounding areas of sample stages on which a sample is held are in not only an air atmosphere, but also special gas atmospheres such as nitrogen and oxygen, and pressures thereof range widely from 1×105 Pa serving as atmospheric pressure to 1×10−7 Pa called high vacuum.
With respect to conventional sample holders, a high corrosion-resistant material has been used as a material in accordance with these various processes and atmospheres, and a sample suction device working out by using mechanical force such as a spring, differential pressure, or electrostatic force has been used as a means for holding a sample.
In recent years, in accordance with further miniaturization and high-density technology of semiconductor integrated circuits, there have been recognized various problems that particles generated by frictional wear between the sample and a sample holder at the time of holding a sample attach to the sample, particles getting into flaws existing on the surface of the sample reattach sporadically due to external force such as vibration, and the like.
On these problems, conventionally, a method for decreasing contact areas between a sample and the sample holder, a method for reducing frictional wear by smoothing contact parts, a method for making contact parts with a sample into curved shapes, and further a method for grinding surfaces of contact parts by using abrasive grains or ultrasonic waves and the like have been used.
In Patent Document No. 1, there has been proposed a vacuum suction device in which a concave notched part is provided in one principal surface of a base substance formed of ceramics, and a plurality of protrusions are provided on the bottom surface of the concave notched part. These protrusions form various shapes. There are a circular truncated cone, a truncated pyramid, and a hemisphere which are taper shapes from the basic parts toward the top faces, or a shape in which cylindrical columns with different diameters are piled up, and the like. There is disclosed that the generations of particles and contaminants due to contacting a sample are greatly reduced by decreasing the areas of the tip faces of the protrusions, or by making the widths of the tip faces of the protrusions 0.1 mm.
In Patent Document No. 2, there has been disclosed a sample suction device in which a fixation plane to hold a sample is made to be a concavo-convex plane in which protrusions or grooves are formed on a base substance, and both of the top faces and the side faces of the convex parts of the concavo-convex plane and the bottom faces of the concave parts of the concavo-convex plane are grinded by using abrasive grains. In accordance therewith, the apical angle parts are decreased at contact portions with the sample on the fixation plane, and it is possible to inhibit particle generation. Further, there has been disclosed that it is possible to reduce reattachment of particles at the time of desorbing the sample held on the fixation plane from the fixation plane by a lift pin.
In Patent Document No. 3, there has been disclosed a sample suction device in which a holding part to hold a sample is capable of movement such as rotating, and it is possible to eliminate particles attaching to the holding part during movement. There has been disclosed a method for this sample suction device in which the holding part is made as a spherical body or a spinning roller to be sandwiched by a retainer, and particles attaching to the holding part are eliminated by rotating the holding part by directly moving the retainer.
In Patent Document No. 4, there has been disclosed a sample suction device in which a DLC (Diamond Like Carbon) film with a thickness of 3 to 40 μm is formed on a surface of a base substance, and defective parts and apical angle parts of the base substance are covered with the DLC film, which reduces particle generation due to wearing of a sample at the apical angle parts.
In Patent Document No. 5, there has been disclosed a vacuum chuck in which a chuck plane is formed from a large number of ceramic spherical bodies which are arrayed as one layer on a surface of a ceramic base substrate to be directly joined to the base substrate. It was disclosed that air intake holes are provided to gaps among the ceramic spherical bodies, and even if particles attach to the edges of the opening portions of the air intake holes, the particles are easily eliminated by suction from the air intake holes formed on the base substrate.    Patent Document No. 1: Japanese Unexamined Patent Publication No. 10-242255    Patent Document No. 2: Japanese Unexamined Patent Publication No. 2003-86664    Patent Document No. 3: Japanese Unexamined Patent Publication No. 10-70179    Patent Document No. 4: Japanese Unexamined Patent Publication No. 2005-101247    Patent Document No. 5: Japanese Unexamined Patent Publication No. 5-285764